Acid hydrolases. Assay of activity and latency in the varied mixed cell populations of canine gastric mucosa.

The specific enzymic properties, membrane or particle binding capacities, and the total activities of certain acid hydrolases, including cathepsin D, acid phosphatase, arylsulfatase, and five acid glycosidases have been compared in normal canine antral and fundic mucosae and in liver. The two major regions of the gastric mucosa, whose cell populations are comparable in type but have very distinct functions, also differ in many properties of their lysosomal enzymes. These differences necessitate several major modification in their method of assay. Using optimal conditions, the activities of most of these enzymes were found to differ: levels in the antrum, in spite of its high water and mucin-glycoprotein content, were significantly greater, suggesting that the high lysosomal hydrolytic activity may be associated with the rapid autophagic processes of normal turnover of its surface epithelial and mucous neck cells. Lysosomal membrane stability or latency is also greater in the antrum; this may account, in part at least, for antral resistance to erosions brought about by stress.